KUDOS to the Federal Housing Finance Agency, overseer of Fannie Mae and Freddie Mac, the crippled mortgage finance giants. While some in Washington have continued to coddle the big banks even after they drove our economy into the ditch, this agency seems serious about recovering money for taxpayers by holding bad financial actors to account.

The agency announced last Monday that it had issued 64 subpoenas to a throng of unidentified financial services institutions, seeking documents related to mortgage securities that Fannie and Freddie bought from Wall Street during the boom years.

The subpoenas are designed to tell the agency what many of us want to know: How did Wall Street package and sell private-label mortgage securities to investors, even though the nature and quality of some of the loans crammed inside those tidy little packages were, at best, suspect?

Once that question has been answered, Fannie and Freddie can force the institutions that sold the securities to repurchase the improper loans, allowing taxpayers to recover some of the losses they’ve swallowed on Fannie’s and Freddie’s federal bailout.

Investigating this aspect of the mortgage mess seems a pretty logical step for a regulator. But in the topsy-turvy world of Washington, the housing finance agency’s move is unusually aggressive. Edward J. DeMarco, its acting director, seems to be that rarity — a regulator who not only talks about looking out for the taxpayer, but actually does something about it.

The subpoenas went to companies that act as trustees for mortgage pools or that service the loans in them. The housing finance agency wants to see loan files and transaction documents related to those pools, including mortgage applications and property appraisals. Recipients of the subpoenas have 30 days to produce the requested documents. Additional subpoenas may follow, it said.

The agency had to resort to subpoenas, it said, because when it asked the institutions for the records it got nowhere for many months. “Difficulty in obtaining the loan documents has presented a challenge to the enterprises’ efforts” to ascertain whether losses at the companies are the responsibility of others, its press release said.

Fannie and Freddie bought only the highest-rated pieces of these deals, but they bought buckets of them. During 2006-7, these entities bought $294 billion of so-called private-label securities. Not all of these purchases are under scrutiny, the agency said.

It is clearly turning up the heat on the major players in mortgage servicing and securitization. Among the bigger trustees in the business are Deutsche Bank and the Bank of New York, while loan servicers include Bank of America and many more. None of the banks would confirm if they had received subpoenas.